Semiconductor light source

ABSTRACT

A light source may comprise a thermally conductive frame comprising a base and a faceted portion extending from the base. The faceted portion may comprise a plurality of facets spaced circumferentially thereabout. Additionally, a hollow passageway may extend through the base and axially through the faceted portion. A plurality of LED chips may be arranged on the plurality of facets to provide an emission of light in an arc of 360 degrees.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 12/785,203, filed May 21, 2010, which is a continuation of U.S.patent application Ser. No. 11/397,323, filed Apr. 4, 2006, now U.S.Pat. No. 7,728,345, which is a continuation-in-part of U.S. patentapplication Ser. No. 10/773,123, filed on Feb. 5, 2004, now abandoned,which is a continuation-in-part of U.S. patent application Ser. No.09/939,339, filed on Aug. 24, 2001, now U.S. Pat. No. 7,224,001, thedisclosures of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of light sources forilluminating physical spaces and, more particularly, to light sourcescomprising one or more semiconducting light emitting diodes (LEDs).

BACKGROUND

This disclosure pertains to light sources, such as light bulbs, forilluminating physical spaces. In particular, the difficulty ofgenerating sufficient light with a light emitting diode (LED) lightsource to illuminate a physical space is addressed. In the past, LEDlights were often restricted to serving as accent lighting due toinsufficient light output.

SUMMARY

A 3-dimensional multiple-faced lead frame is used to create a compactand efficient light source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective view of a light source for illuminating aphysical space using a 3-dimensional multiple-faced lead frame;

FIG. 2 depicts a cross-sectional view of the device of FIG. 1;

FIG. 3 depicts some example shapes for lead frame;

FIG. 4 depicts a perspective view of an alternative light source using a3-dimensional multiple-faced lead frame;

FIG. 5 depicts a cross-sectional view of the device of FIG. 4;

FIG. 6 depicts a perspective view of another alternative light sourceusing a 3-dimensional multiple-faced lead frame;

FIG. 7 depicts a perspective view of another alternative light sourceusing a 3-dimensional multiple-faced lead frame; and

FIG. 8 depicts a cross-sectional view of the device of FIG. 7.

DETAILED DESCRIPTION

There are several ways to increase LED output. One is to increase thesize of the chips. Another is to utilize more chips in the light source.Increasing chip size creates several issues. First, it increases costbecause production processes must be more precise as chip sizeincreases. Second, the chip will have a lower emitting efficiency due toheat issues. When an LED chip is enlarged, heat is also proportionallyincreased. Large amount of heat are not easily removed from the chip,therefore, the overall temperature of the chip will be increased andlight emitting efficiency will decrease.

In the prior art, multiple LED chips were integrated together in 2dimensional plate form to achieve an increase in power. Integration ofmultiple chips in a 2 dimensional array also has disadvantages of alarge footprint and a complicated production process. This disclosurerelates to structures and processes for creating an LED light sourceusing a 3-dimensional multiple facet lead frame to create a compact andefficient light source.

FIG. 1 depicts an LED light source 100 having a 3-dimensional lead framewith multiple facets or faces to house multiple LED chips. A 3dimensional lead frame 101 is provided with a shaft 102 and a standardscrew thread 103. With the thread, the light source can be twisted intoa traditional light socket to replace prior art incandescent bulbs.Faces or facets 104 are provided on the lead frame 101. The lead frame101 itself acts as cathode for the LED 100. A cap 105 of the anode isprovided with an extended pin 106. The cathode and anode are isolated byan insulation layer 107. The LED chip(s) 108 are placed on each facet ofthe lead frame 101. One or more chips per facet or face can be used. Awire 109 connects the anode of the chip 108 to the anode 105 of the leadframe and wire 110 connects the cathode of the chip to the main body ofthe lead frame. The lead frame with chips is covered by an epoxy cap120. The epoxy cap 120 acts as optical lens for light emitted from chipand also as protection layer for the chip and lead frame. The overalldesign achieves the following features for a light source: emission oflight in an arc of 360 degrees; the light source is easily replaceable,and the light source is completely sealed and water proof.

FIG. 2 depicts cross section 200 of the LED described in FIG. 1. Leadframe 201 is shown in cross section. Base 202 is the cathode of the LED,and the shaft 203 of the cathode connects to a threaded fitting 204. Thefacet portion 205 of the cathode is almost perpendicular to the base 202in this example. Based on design requirements, the facet may not beperpendicular to the base. Cap 206 of the anode of the lead frame has apin 207 extending through cathode of lead frame. The anode and cathodeare isolated by an insulation material 208. The insulation material canbe epoxy, AlO, and any other materials having insulation properties. Theinsulation layer will electrically insulate the anode and cathode. Chipssuch as 209 are attached to facets of the lead frame. Chip 209 isconnected to anode 206 using wire 210 a and is connected to cathode 201using gold or Al wire 210 b. There is a light conversion layer 211coated on top of chip 209 to convert the emitted from the chip intodifferent color when such conversion is required. The lead frame, anode,cathode and chips are covered by an epoxy cap 212. The epoxy cap 212acts as both optical lens and also as a protection layer for lead frameand chips.

FIGS. 3 a-3 f depict example profiles for a lead frame. The main shapeof the lead frame is defined by the shape of cathode. The anode has thesame shape as cathode and both can be any shape as desired. FIG. 4depicts a multiple facet LED with a surface mount type package 400. Abase 401 is provided that acts as a heat conductor. It can be made fromelectrically insulating material, such as ceramics, plastics, etc. Onthe base 401, electrodes 402 and 403 are laid on one side of the baseand electrodes 404 and 405 are laid on the other side the base. Anodes402 and 404 are also provided to complete the circuit with cathodes 403and 405. Electrodes may be made by coating a metal layer like Al or Auor other alloys on top of a ceramic base. On top of the 401 base, theresits a cathode 407 of lead frame 406. The cathode 407 of lead frame 406is connected to base 401. There are multiple vertical facets 408connected to base 407. The anode cap 409 is placed on top of the cathodelead frame with an insulation layer 410 in between. A chip 411 is laidon one of the facets. The chip 411 is connected to cathode and anodethrough wires 412 and 413. The lead frame and chips are capped withepoxy layer 414, which will serve as a cap and also as an optical lens.Options include a surface mount type as well as a printed circuit boardwith various electronics.

FIG. 5 depicts a cross-sectional view of an LED 500 such as that alreadydiscussed with respect to FIG. 4. A lead frame cathode 501 is providedwith a base 502. A cap 504 is provided as well as an anode pin 505. Aninsulation layer 506 is located between the cathode and anode. An LEDchip 507 is located on one of the frame faces such as 503. An optionalphosphor coating layer 508 may be used for light color conversion. Wires509 and 510 connect the chip to anode and cathode. An epoxy cap 511covers the whole lead frame. The base profile of the LED is shown at512. The material for base 512 has a property for heat conduction andelectrical insulation. Electrodes are laid using metal coating layers513 and 514 for cathode and anode, respectively. The cathode 503 of thelead frame is connected to cathode 513 in the base through connection515 and anode 505 of the lead frame is connected to anode in the base514 through connection 516.

FIG. 6 depicts another packaging style with light only emitted in onedirection. Note the fewer faces on the frame. The LED 600 has a base 601and electrodes 602, 603, 604, and 605 respectively. The lead frame 606only has multiple facets in one direction and chips are placed on thefacet. There is an epoxy cap 607 to protect the lead frame and LEDchips. The light will be emitted in one direction. Such light can beused for different backlighting applications.

FIG. 7 depicts a cylinder style of two multiple face lead framesconnected to each other. LED 700 has two cathode lead frames 701 and 702with multiple facets. One anode 703 is placed to next to cathode 701with insulation layer 704. A chip 705 is placed on one of facets withwire connections to anode and cathode. Another anode 706 which issandwiched by two insulation layers 708 and 709 is placed between frames701 and 702. LED chip 709 is placed on top of one of faces in 702. Anepoxy cap 711 is molded to cover the whole lead frame and components.Electrodes 712 and 713 are set up as the leads for anode and cathode,respectively.

FIG. 8 depicts a cross sectional view of the LED illustrated in FIG. 7.This view shows the arrangement between anode and cathode. In the anode,there is a contact 801. Platforms 802 and 803 connected by a rod 804.There are two bonding facets 805 and 806 on platforms 802 and 803,respectively. Two cathodes 807 and 808 with multiple facets areconnected through connection rod 809. Insulation layers 810 and 811 areused to fill the space between anode and cathode. The contact forcathode is 812. A chip 813 is mounted on a facet of the lead frame. Anoptional phosphor coating 814 can provide wavelength conversion. Wires815 and 816 connect the chip to anode and cathode.

A light source with a multiple faceted lead frame with LED chip(s)attached to each facet can be provided to integrate multiple chip(s)into one small foot print package. The number of facets on the leadframe can be one to infinity depending on requirements. The lead frameis a 3-dimensional device with facets angled in desired directions.Cathode and anode of the lead frame isolated with insulation materials.One or more LED chips can be attached to each facet. A light conversionlayer may be coated on top of LED chips to convert the color of thelight emitted by the chips. The lead frame is covered by an epoxycapsule as both protection and optical lens. The lead frame can be adiode type with a thread on the base or surface mount type withelectrodes on the base. The multiple faceted lead frame can be onesection or multiple sections to form a bar type of light source. A whitelight source with multiple facet lead frame by applying a phosphor ontop of a blue chip. The lead frame is made from a heat conductingmaterial in order to draw heat away from the chips and avoid loss oflumen output due to heat effect.

While the present invention has been described and illustrated inconjunction with a number of specific embodiments, those skilled in theart will appreciate that variations and modifications may be madewithout departing from the principles of the invention as hereinillustrated, described, and claimed. The present invention may beembodied in other specific forms without departing from its spirit oressential characteristics. The described embodiments are to beconsidered in all respects as only illustrative, and not restrictive.All changes which come within the meaning and range of equivalency ofthe claims are to be embraced within their scope.

What is claimed is:
 1. A light source, comprising: a base; a facetedportion arranged on the base, and comprising a bottom width and aplurality of facets; a hollow passageway surrounded by the plurality offacets, and comprising a top opening and a bottom opening; a pin passingthrough the hollow passageway from the top opening to the bottomopening; an electric insulator arranged between the pin and the facetedportion; a shaft arranged under the base and having a top widthsubstantially equal to the bottom width in a cross-sectional view; and aplurality of LED chips arranged on the plurality of facets andelectrically connected to the pin.
 2. The light source of claim 1,wherein each facet of the plurality of facets has at least one LED chippositioned thereon.
 3. The light source of claim 1, wherein at least oneLED chip of the plurality of LED chips is covered with a lightconversion layer.
 4. The light source of claim 3, wherein each LED chipof the plurality of LED chips is covered with a light conversion layer.5. The light source of claim 4, wherein the light conversion layercomprises a phosphorous material.
 6. The light source of claim 1,wherein at least one of the plurality of facets has an orientation notparallel to the base.
 7. The light source of claim 1, further comprisinga transparent cap sealing the plurality of LED chips and the facetedportion.
 8. The light source of claim 1, wherein the electric insulatorhas a portion arranged on the top opening.
 9. A light source,comprising: a base; a faceted portion arranged on the base, andcomprising a bottom width and a plurality of facets; a hollow passagewaysurrounded by the plurality of facets, and comprising a top opening anda bottom opening; a pin passing through the hollow passageway from thetop opening to the bottom opening; an electric insulator arrangedbetween the pin and the faceted portion; a shaft arranged under the baseand having a top width substantially equal to the bottom width in across-sectional view; and a plurality of LED chips electricallyconnected to the pin, each LED chip covered by a light conversion layer,the plurality of LED chips arranged on each respective facet of theplurality of facets to provide an emission of light in an arc of 360degrees.
 10. The light source of claim 9, wherein the light conversionlayer comprises a phosphorous material.
 11. The light source of claim 9,wherein the electric insulator has a portion arranged on the topopening.
 12. The light source of claim 9, wherein the electric insulatorhas a surface coplanar with an outer surface of the faceted portion. 13.The light source of claim 1, wherein the electric insulator has asurface coplanar with an outer surface of the faceted portion.